Edge Continued Evolution, Improved Channel Request Method And System

ABSTRACT

The present invention is a method and system adapted to facilitate, between a mobile station (MS) and network, an indication of support for reduced time transmission interval (RTTI). The MS can provide a base station system (BSS) with an indication of its multislot capability within an access burst sent at the start of a contention based access. In another aspect, the MS can indicate support for a new Immediate Assignment message as the conventional Immediate Assignment message can only assign single timeslots. The present invention enables the Radio Access Network (RAN) to assign RTTI and more than one timeslot for GPRS/EDGE temporary block flows (TBFs) during an Access Grant Channel (AGCH) assignment. The method of the present invention can be implemented in a computer program product or distributed software adapted to be loaded into at least one or a plurality of memory locations and executed by at least one or a plurality of respective computer processors.

RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 12/444,525 filed Apr. 6, 2009, which is a 371 of InternationalApplication No. PCT/SE2007/050708, filed Oct. 4, 2007, which claims thebenefit of U.S. Provisional Application No. 60/828,287, filed October,2006, the disclosures of which are fully incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to wireless communication systems. Moreparticularly, and not by way of limitation, the present invention isdirected to a system and method for reducing latency between WidebandCode Division Multiplex Access (WCDMA) systems and Enhanced Data GSMEnvironment (EDGE) systems, EDGE is a wireless Third Generation (3G)technology that allows it to increase data transmission rate and improvedata transmission reliability. EDGE can be used for any packet switchedapplication such as an Internet connection. EDGE is implemented as anadd-on enhancement to 2G and 2.5G Global System for MobileCommunications (GSM) and General Packet Radio Service (GPRS) networks,making it easier for existing GSM carriers to upgrade to it. AlthoughEDGE requires no hardware or software changes to be made in GSM corenetworks, base stations must be modified to implement EDGE. EDGEcompatible transceiver units must be installed and the base stationsubsystem (BSS) must be upgraded to support EDGE. New mobile terminalhardware and software are also required to decode/encode the newmodulation and coding schemes and carry the higher user data rates toimplement new services. However, in the continuing evolution of the 3Gstandard, WCDMA has been developed. More technically, WCDMA is awideband spread-spectrum mobile air interface that utilizes the directsequence Code Division Multiple Access (CDMA) signaling method toachieve higher speeds and support more users compared to theimplementation of time division multiplexing (TDMA) used by 2G GSMnetworks. WCDMA has been developed into a complete set ofspecifications, a detailed protocol that defines how a mobile phonecommunicates with the tower, how signals are modulated, how datagramsare structured, and system interfaces are specified allowing freecompetition on technology elements.

The Third Generation Partnership Project (3GPP) continues to evolve thetechnology used in wireless communication systems from EDGE to WCDMA. Inconnection therewith, an objective is to obtain seamless workabilitybetween WCDMA and EDGE by reducing latency. This is critical insymmetric service applications such as Voice over IP (VoIP), interactivegaming and push-to-talk over cellular (PoC).

In a conventional system, the mobile station (MS) is capable ofindicating to the RAN that it can handle more than 1 time slot (TS) inthe uplink, however the RAN is restricted by the current 3GPP standardto assigning only 1 TS for an uplink TBF until it finds out about the MScapabilities, either during the second phase of a two phase access or byquerying the Serving GPRS Support Node (SGSN) for this information forthe case of a one phase access. The result of this is a slower ramp-upin throughput and an increased delay. This restriction increases theinitial delay for services like VoIP and Push-to-talk (PoC).

It would be advantageous to have a system and method that reduceslatency between WCDMA systems and EDGE systems such that it overcomesthe disadvantages of the prior art. The present invention provides sucha system and method.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention is directed to a method and systemfor an MS to indicate support for reduced time transmission interval(RTTI). Note that a 10 ms round trip time (RTT) can be used immediatelyinstead of using 20 ms RTT in the beginning and then upgrading it to 10ms RTT. In another aspect, the present invention is directed to a methodand system for the MS to provide a base station system (BSS) with anindication of its multislot capability (the new Rel. 5 multislotclasses) within an access burst sent at the start of a contention basedaccess. In yet another aspect, the present invention is directed to amethod and system for an MS to indicate support for a new ImmediateAssignment message as the conventional Immediate Assignment message canonly assign single timeslots. The present invention enables the RadioAccess Network (RAN) to assign RTTI and more than one timeslot forGPRS/EDGE temporary block flows (TBFs) TBFs during an Access GrantChannel (AGCH) assignment. The method of the present invention can beimplemented in a computer program product or distributed softwareadapted to be loaded into at least one or a plurality of memorylocations and executed by at least one or a plurality of respectivecomputer processors.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the following section, the invention will be described with referenceto exemplary embodiments illustrated in the figures, in which:

FIG. 1 is a table showing the legacy format of an Enhanced GPRS (EGPRS)Packet channel request;

FIG. 2 is a table illustrating the present invention of a packet channelrequest without the option of indicating RTTI;

FIG. 3 illustrates defined coding for the information field indicatingthe EGPRS multislot class of the MS:

FIG. 4 is a table illustrating the present invention of a packet channelrequest with the option of indicating RTTI;

FIG. 5 illustrates defined coding for the information field indicatingthe EGPRS multislot class of the MS;

FIG. 6 illustrates defined coding for the information field indicatingthe TTI capabilities of the MS;

FIG. 7 is a table is an example how many timeslots a mobile stationsupports in downlink (RX) and uplink (TX) respectively, depending on themultislot class it supports;

FIG. 8 is a table illustrating a EGPRS packet channel request;

FIG. 9 is a table illustrating the gain for transmitting 1000 bytes ofpayload;

FIG. 10 is a flow chart of the method of an aspect of the presentinvention; and

FIGS. 1A and 11B are block diagrams of the system and nodes in which anaspect of the method of the present invention can be implemented.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the present invention is directed to a method and systemfor an MS to indicate support for RTTI. In another aspect, the presentinvention is directed to a method and system for the MS to provide abase station system (BSS) with an indication of its multislot capabilitywithin an access burst sent at the start of a contention based access.In yet another aspect, the present invention is directed to a method andsystem for an MS to indicate support for a new Immediate Assignmentmessage as the conventional Immediate Assignment message can only assignsingle timeslots. The present invention enables the Radio Access Network(RAN) to assign reduced time transmission interval (RTTI) and more thanone timeslot for GPRS/EDGE temporary block flows (TBFs) TBFs during anAccess Grant Channel (AGCH) assignment. The method of the presentinvention can be implemented in a computer program product ordistributed software adapted to be loaded into at least one or aplurality of memory locations and executed by at least one or aplurality of respective computer processors.

Multislot Assignment

The present invention is a method and system that introduces a new fieldin an Immediate Assignment message sent on AGCH, or alternatively, on anew Multislot Immediate Assignment message, to allocate the MS more than1 TS on the uplink and one or more TS on the downlink. For the RAN to beable to send this message it has to know if the MS is capable ofreceiving it, hence the MS must first indicate to the RAN that it hasthis ability. The only way for an MS to do this is to include newinformation in the access burst sent by the MS at initial system accesson the Random Access Channel (RACH). For the MS to know which RANssupport this new format, the access burst System Information (SI) sentby the RAN must be modified to provide this indication.

Referring to FIG. 1, a table 100 showing the legacy format of anEnhanced GPRS (EGPRS) Packet channel request is provided.

FIG. 2 is a table 200 illustrating the present invention of a packetchannel request without the option of indicating RTTI.

A three (3) bit field named, e.g., MuitislotClassLimited is aninformation field indicating the EGPRS multislot class of the MS. Themultislot class indicated by this field is according 3GPP 45.002. Thecoding is defined in the table 300 of FIG. 3.

FIG. 4 is a table 400 illustrating the present invention packet channelrequest with the option of indicating RTTI.

A three (3) bit field named, e.g., MultislotClassLimited is aninformation field indicating the EGPRS multislot class of the MS. Themultislot class indicated by this field is according 3GPP 45.002. Thecoding is defined in the table 500 of FIG. 5.

A one (1) bit field named, e.g., TICapabilities is an information fieldthat indicates the TTI capabilities of the MS. The coding is defined inthe table 600 of FIG. 6.

FIG. 7 is a table 700, taken from current standard specifications andshows for example how many timeslots a mobile station supports indownlink (RX) and uplink (TX) respectively, depending on the multislotclass it supports. So, the mobile station reports its multislot class (asingle number) to the network, which translates into a number ofattributes (RX, TX, Sum, etc.) in table 7.

An alternative MS indication for RTTI (10 ms RTT) support is nowdiscussed. Instead of using the priority bits it is possible to use oneof the already standardized Training Sequence Codes, FIG. 8 is a table800 illustrating a EGPRS packet channel request. To differentiate the“RTTI support” access from the “Legacy GMSK only support in UL” access,the new “RTTI support” has to be combined with the EGPRS MultislotAccess message. An advantage of the foregoing is that the use ofpriority bits can still be used in a EGPRS Multislot Access message.

Applications such as Conversational VoIP and PoC put significant demandson GERAN. One demand is to support quick access, along with quickestablishment of multislot operation, for applications using protocolswith extensive signaling during service access (such as SIP). Thepresent invention implements this and improves service access for mostapplications in general, and applications such as VoIP and PoC inparticular.

Referring now to FIG. 9, multislot operation can be used 160 ms earlierwith the method of the present invention compared to the conventionalprocedure. As an example, with 3 additional timeslots, 1344 bytes can betransmitted using MCS-5 on 160 ms, and 672 bytes using MCS-2 (assuming0% BLER). Another example is how long time it would take to transmit a1000 bytes large packet. The result is shown in the table 900 of FIG. 9.Again, assuming 0% BLER for simplicity, and the time is from the 0 mstime position in as seen in FIGS. 1, 2 and 3. The results assume a MScapable of 4 TS in the UL. As can be seen in the table 900 of FIG. 9,the gain for transmitting 1000 bytes of payload is 160 ms.

Referring now to FIG. 10, a flow chart 1000 of the method of the presentinvention is presented. As seen therein, in step 1001, a MS identifies atransmit need. In step 1002, the MS accesses the BSS indicating RTTIsupport and/or New immediate Assignment support. In step 1003, the BSSmatches MS support capabilities with current and expectedround-trip-time requirement. In step 1004, the BSS assigns multislotconfiguration and/or RTTI configuration and in step 1005, the round triptime is improved when possible and required.

FIG. 11B is the radio and core network of a wireless telecommunicationssystem in which the method 1000 of the present invention is implemented.FIG. 118 is a block diagram 1101 showing components the system in whichthe present invention is implemented, showing the interfaces between thenodes thereof. As seen therein The MS 1001 is the end-user equipmentthat is coupled via a communication channel (interface Um) to the BSS1102 which controls the radio connection. The BSS 1102 is coupled to thepacket core network 1103 via interface Gb. The packet core network 1103controls the connection between mobile network and internet 1104 viainterface Gi. The internet 1104 is the turning-point in a round-trip.The method of the present invention can be implemented in a computerprogram product or distributed software adapted to be loaded into atleast one or a plurality of memory locations (in the MS 1101 and the BSS1102) and executed by at least one or a plurality of respective computerprocessors (in the MS 1101 and the BSS 1102).

As will be recognized by those skilled in the art, the innovativeconcepts described in the present application can be modified and variedover a wide range of applications. Accordingly, the scope of patentedsubject matter should not be limited to any of the specific exemplaryteachings discussed above, but is instead defined by the followingclaims.

1-25. (canceled)
 26. A method of reducing latency in a communicationschannel, comprising the steps of: receiving, by a Radio Access Network(RAN), an indication in a packet channel request from a mobile station(MS) where the indication indicates that the MS supports a reduced timetransmission interval (RTTI); including, by the RAN, an additional fieldin an Immediate Assignment message sent on an Access Grant Channel(AGCH); and, using, by the RAN in response to receiving the indication,the additional field to allocate to the MS more than one time slot (TS)on an uplink of the communications channel and one or more time slots ona downlink of the communications channel.
 27. The method of claim 26,wherein the communications channel includes a Wideband Code DivisionMultiplex Access (WCDMA) system and an Enhanced Data GSM Environment(EDGE) system.
 28. The method of claim 27, further comprising the stepof assigning, by the RAN, the reduced time transmission interval (RTTI)and more than one timeslot for GPRS/EDGE temporary block flows (TBFs)during an AGCH assignment.
 29. The method of claim 28, furthercomprising the step of indicating by the MS to the RAN that it has theability to accept the Immediate Assignment message.
 30. The method ofclaim 29, further comprising the step of including, by the MS,information in an access burst sent by the MS at initial system accesson the Random Access Channel (RACH) indicating the ability of the MS toaccept the Immediate Assignment message.
 31. The method of claim 30,further comprising the step of modifying access burst System Information(SI) sent by the RAN to indicate to the MS the ability of the RAN tosupport the Immediate Assignment message.
 32. The method of claim 26,wherein the Immediate Assignment message is a Multislot ImmediateAssignment message.
 33. The method of claim 26, wherein the MS byindicating support for the RTTI indicates that a 10 ms round trip time(RTT) is to be used immediately instead of using 20 ms RTT in beginningand then upgrading to 10 ms RTT.
 34. A method of reducing latency in acommunications channel, comprising the steps of: identifying, by amobile station (MS), a transmit need; accessing, by the MS, a basestation subsystem (BSS); indicating, by the MS, the support thereof forat least one of a reduced time transmission interval (RTTI) and NewImmediate Assignment message; matching, by the BSS, the MS supportcapabilities with current and expected round trip time requirements;assigning, by the BSS, multislot configuration and RTTI configuration;using, by the BSS in response to the indicating step, an additionalfield in an Immediate Assignment message sent on an Access Grant Channel(AGCH) so as to allocate to the MS more than one time slot (TS) on anuplink of the communications channel and one or more time slots on thedownlink of the communications channel.
 35. The method of claim 34,wherein the MS by indicating support for the RTTI indicates that a 10 msround trip time (RTT) is to be used immediately instead of using 20 msRTT in beginning and then upgrading to 10 ms RTT.
 36. The method ofclaim 34, wherein the indicating step further comprises indicating, bythe MS, the support thereof for the at least one RTTI and the NewImmediate Assignment message by inserting an indication in a packetchannel request from the MS where the indication indicates that the MSsupports a reduced time transmission interval (RTTI).
 37. The method ofclaim 34, wherein the indicating step further comprises indicating, bythe MS, the support thereof for the at least one RTTI and the NewImmediate Assignment message by inserting information in an access burstsent by the MS at initial system access on a Random Access Channel(RACH).
 38. A system of reducing latency in a communications channel,comprising: a Radio Access Network (RAN) configured to receive anindication in a packet channel request from the MS where the indicationindicates that the MS supports a reduced time transmission interval(RTTI); the RAN configured in response to receiving the indication touse a field in an Immediate Assignment message sent on AGCH so as toallocate to a mobile station (MS) more than one time slot (TS) on anuplink of the communications channel and one or more time slots on adownlink of the communications channel.
 39. The system of claim 38,wherein the communications channel includes a Wideband Code DivisionMultiplex Access (WCDMA) system and an Enhanced Data GSM Environment(EDGE) system.
 40. The system of claim 39, wherein the RAN is configuredto assign the reduced time transmission interval (RTTI) and more thanone timeslot for GPRS/EDGE temporary block flows (TBFs) TBFs during anAccess Grant Channel (AGCH) assignment.
 41. The system of claim 40,wherein the MS is configured to indicate to the RAN that it has theability to accept the Immediate Assignment message.
 42. The system ofclaim 41, wherein the MS is configured to include information in anaccess burst sent by the MS at initial system access on a Random AccessChannel (RACH) indicating the ability of the MS to accept the ImmediateAssignment message.
 43. The system of claim 42, wherein the RAN isconfigured to modify access burst System Information (SI) to indicatethe ability to the MS to accept the Immediate Assignment message. 44.The system of claim 38, wherein the Immediate Assignment message is aMultislot Immediate Assignment message.
 45. The system of claim 38,wherein the MS by indicating support for the RTTI indicates that a 10 msround trip time (RTT) is to be used immediately instead of using 20 msRTT in beginning and then upgrading to 10 ms RTT.
 46. A node in awireless communications system adapted to reduce latency in acommunications channel, comprising: at least one computer processor thatexecutes a computer program product or distributed software loaded intoat least one memory location to implement following: receiving from amobile station (MS) an indication for support of at least one of areduced time transmission interval (RTTI) and a New Immediate Assignmentmessage; matching MS support capabilities with current and expectedround trip time requirements; assigning a multislot configuration andRTTI configuration; using, in response to the receiving operation, anadditional field in an Immediate Assignment message sent on an AccessGrant Channel (AGCH) so as to allocate to the MS more than one time slot(TS) on an uplink of the communications channel and one or more timeslots on the downlink of the communications channel.
 47. The node ofclaim 46, wherein the node is a base station subsystem (BSS).
 48. Thenode of claim 46, wherein the at least one computer processor executesthe computer program product or distributed software loaded into theleast one memory location to implement following: introducing a field inthe Immediate Assignment message sent on the AGCH so as to allocate tothe mobile station (MS) more than one time slot (TS) on an uplink of thecommunications channel and one or more time slots on a downlink of thecommunications channel.
 49. The node of claim 48, wherein thecommunications channel includes a Wideband Code Division MultiplexAccess (WCDMA) system and an Enhanced Data GSM Environment (EDGE)system.
 50. The node of claim 49, wherein the at least one computerprocessor executes the computer program product or distributed softwareloaded into the least one memory location to implement following:assigning the reduced time transmission interval (RTTI) and more thanone timeslot for GPRS/EDGE temporary block flows (TBFs) TBFs during anAccess Grant Channel (AGCH) assignment.
 51. The node of claim 50,wherein the at least one computer processor executes the computerprogram product or distributed software loaded into the least one memorylocation to implement following: receiving an indication from the mobilestation (MS) indicating that the MS has the ability to accept anImmediate Assignment message.
 52. The node of claim 51, wherein the atleast one computer processor executes the computer program product ordistributed software loaded into the least one memory location toimplement following: receiving the indication in an access burst sent bythe MS at initial system access on a Random Access Channel (RACH)indicating the ability of the MS to accept the Immediate Assignmentmessage.
 53. The node of claim 52, wherein the at least one computerprocessor executes the computer program product or distributed softwareloaded into the least one memory location to implement following:modifying access burst System Information (SI) sent by the node toindicate the MS the ability of the RAN to support the ImmediateAssignment message.
 54. The node of claim 46, wherein the ImmediateAssignment message is a Multislot Immediate Assignment message.
 55. Thenode of claim 46, wherein the MS by indicating support for the RTTIindicates that a 10 ms round trip time (RTT) is to be used immediatelyinstead of using 20 ms RTT in beginning and then upgrading to 10 ms RTT.56. The node of claim 46, wherein the receiving operation furthercomprises receiving an indication in a packet channel request from theMS indicating the support thereof for the at least one RTTI and the NewImmediate Assignment message.
 57. The node of claim 46, wherein thereceiving operation further comprises receiving information in an accessburst sent by the MS at initial system access on a Random Access Channel(RACH), where the information indicates support by the MS for the atleast one RTTI and the New Immediate Assignment message.
 58. A method ofreducing latency in a communications channel, the method implemented bya Mobile Station (MS) comprising the steps of: receiving, from the RadioAccess Network (RAN), a modified access burst System Information (SI) toindicate to the MS the ability of the RAN to support a new ImmediateAssignment message to allocate to the MS more than one time slot (TS) onan uplink of the communications channel and one or more time slots onthe downlink of the communications channel; sending an access burst tothe RAN at initial system access on the Random Access Channel (RACH)indicating the ability of the MS to accept the new Immediate Assignmentmessage; and receiving, from the RAN in response to the sending step,the new Immediate Assignment message sent on an Access Grant Channel(AGCH), where the new Immediate Assignment message is used to allocateto the MS more than one time slot (TS) on an uplink of thecommunications channel and one or more time slots on the downlink of thecommunications channel.
 59. The method of claim 58, wherein the MS byindicating support for the new Immediate Access message indicates that a10 ms round trip time (RTT) is to be used immediately instead of using20 ms RTT in beginning and then upgrading to 10 ms RTT.
 60. A method ofreducing latency in a communications channel, the method implemented bya Radio Access Network (RAN) comprising the steps of: sending, to aMobile Station (MS), a modified access burst System Information (SI) toindicate to the MS the ability of the RAN to support a new ImmediateAssignment message to allocate to the MS more than one time slot (TS) onan uplink of the communications channel and one or more time slots onthe downlink of the communications channel; receiving an access burstfrom the MS at initial system access on the Random Access Channel (RACH)indicating the ability of the MS to accept the new Immediate Assignmentmessage; sending, to the MS in response to the receiving step, the newImmediate Assignment message sent on an Access Grant Channel (AGCH),where the new Immediate Assignment message is used to allocate to the MSmore than one time slot (TS) on an uplink of the communications channeland one or more time slots on the downlink of the communicationschannel.
 61. The method of claim 60, wherein the MS by indicatingsupport for the new Immediate Access message indicates that a 10 msround trip time (RTT) is to be used immediately instead of using 20 msRTT in beginning and then upgrading to 10 ms RTT.